Portable flashlights are normally used only seldom but are an indispensable aid in exceptional instances such as, e.g. a current outage in the home, on unlit paths, for illuminating doorbell signs, house numbers or the like, or in the case of a breakdown for illuminating the engine area or the like.
The earlier customary use of incandescent bulbs allowed the battery capacity to die down relatively quickly so that in certain instances the residual capacity of the batteries was no longer sufficient to generate a sufficiently large voltage.
A significant improvement was already achieved in that the incandescent bulb was replaced by a light-emitting diode. Light-emitting diodes require considerably less current for operation so that the total illumination time per battery set is correspondingly greater.
In addition, in contrast to incandescent bulbs light-emitting diodes are relatively resistant to impacts and jolts so that their service life is also multiply lengthened. Finally, light-emitting diodes are smaller than incandescent bulbs so that a distinct miniaturization of the flashlight was able to be achieved in conjunction with the lower current requirement. This even went so far that small flashlights had a diameter that was less than 1 cm and the length of the flashlights was 5 cm or less. Such flashlights can be carried on key rings, so that they are there when needed.
Other potential savings with flashlights result from the use of rechargeable batteries that, although they are more expensive than disposable batteries, can be recharged many times.
Chargers known from the state of the art are used for recharging that are usually set up for connection to a power outlet and have compartments for several batteries and that can also have different shapes. For recharging, the batteries must be removed from the flashlight and inserted into the charger, that then remains connected to the power for several hours before the batteries are available again.
DE 732 364 describes a charger and flashlight with built-in battery suitable for connection to line. The flashlight head and the externally exposed charge contacts of the rod-shaped flashlight can be set in a cup-shaped compartment of the charger in such a manner that they can be anchored in a certain position in a bayonet manner, during which a closed contact is made between the contacts of the charger and of the flashlight.
U.S. Pat. No. 3,749,905 describes a charger for the batteries of a flashlight that has a line connection at whose end is a plug that can be inserted into the socket of a car cigarette lighter. The charger housing has contact seats that can be connected to corresponding contacts of the flashlight on its outer housing in order to close the circuit for recharging the batteries. This apparatus has the disadvantage that the charger must either be fastened to a console in the car so that it is optically disturbing even when not in use charging. As an alternative, the charger can be set in the foot space or on the passenger seat; however, such movable parts are undesired on account of the increased danger of an accident during sharp braking or rapid curve travel.
DE 36 36 968 C2 describes a rechargeable flashlight consisting of a central part containing a battery and a double charge circuit and comprising a line plug arrangement on one end and on the opposite end an adapter plug for a car socket, especially a cigarette-lighter connection. Furthermore, this flashlight comprises a reflector part that can be coupled to the central part and that extends over the adapter plug as well as comprises a plug cap that covers the line plug and in which an apparatus for separating the accessible contacts of the adapter plug is arranged in the central part, which apparatus is active during the charging of the battery via the line plug arrangement. According to the invention a switch that can be activated via a plunger is provided for separating the adapter plug from the line voltage during charging of the battery via the line plug arrangement, which switch is intended to ensure that it is opened at the beginning of the drawing off of the cap covering the accessible contacts and of the reflector part, thus interrupting the electrical connection between these contacts and the line voltage. However, this arrangement has the disadvantage of taking up quite a bit of space.